Hi everyone !
After being trapped in a "digging/tweaking/tuning/flying/repeat" loop for 3 weeks, I've finally managed to have a stable yet fully aerobatic tricopter which loiters fine and can be flown FPV with no probs. However, I still have some issues regarding the RTL and Auto functions. It took ages to set everything up and solve some problems which jeopardized the whole flight capabilities of the plateform. So I tried to remember everyone of them, describe them and add the solution I've found to be able to help beginners tricopter builder in their firsts steps with Arducopter. I take absolutely no credit to any of the fixes mentionned here, since it's pretty much a compilation of solutions I found here and there, but I sincerely thank the numerous contributors of the DIYdrones community for helping people so much, without even knowing it.
To this day, using an APM2 to control a tricopter is a tricky thing to do. Setting up a more or less flyable tri is easily achieved, but having it fine-tuned and capable of performing sharp maneuvers without shaking like my grand-fathers hand as well as having a good yaw authority while keeping the heading smooth and precise require a lot more work. I will stubbornly stand against anyone daring to say the opposite. Arducopter (v2.4~2.6) might be PNF for other platforms, it absolutely ain't for the tricopter. However, a carefully tuned APM2 will deliver naza-like stability while remaining fully aerobatic if you take the time to show him love. So, it might be a very steep learning curve, but the result is IMO worth the hair loss. And after all, hairs are by far more disposable than the kidney you have to sell to buy a wookong anyway.
If you decide to take the plunge, hook the tricopter to a KKBoard and ensure everything is flying fine. This important step will rule out platform-dependant problems such as motors angle, yaw servo center and throw, yaw assembly wiggling, EM noise ... So don't skip it, it may save you a lot of time and some wig costs too. Once your tri is flying OK with the KKBoard, you'll know for sure that any issue encountered will be Arducopter-related. Time to install the APM2. Be sure to read the wiki thoroughly before, every aspect of the installation being perfectly described there.
Tip : it may be practical to glue some 3 pins male connectors through the cockpit, pointed outside (I use the infamous tupperware cockpits) so that the cockpit containing all the brains electronics (APM, OSD, telemetry...) remains watertight and can be mounted with velcro [yes, the blue one] on the platform. This way, exchanging platforms might just be as easy as exchanging cockpits, connecting ESCs and loading parameters or reflashing the firmware. Just be sure to tape the wires from servos and ESCs to the platform to avoid them getting disconnected in flight by vibrations and to punch a tiny hole on the bottom for the baro sensor.
So there were the most tenacious problems I encountered until now. If I find new ones, I might update this post to keep it up to date. If I can persuade my sd-dvr to record fpv flights instead of obstinately corrupting my sd cards and my girlfriend to hold a camera instead of crashing a KK tricopter, I might add videos to [hopefully] help newcomers to motivate themselves into building an ardu-tri-copter. In the mean time, don't hesitate to post tricopter-related questions below.
Happy flying !
Question: is flying the Acro mode first and adjusting the AcroP a necessary step prior to moving on to tune the Stable mode?
Comment: I was under the impression that Expo is an adjustable rate to get to the SAME amount of throw; I am questioning how adjusting expo gives more throw ("230%" ). I realize that "dualRate" gives different BUT LESS amount of throw.
I haven't flown a multicopter yet, but I don't think you should have to fly in Acro mode to tune the RateP. That's not the goal of the system.
You are right about the expo. That is usually how it works. But what I did is a hack to give more rate, and expo. So it's like Dual Rates and Expo together. Just a hack to get a better feel within the existing system.
Basic testing done with channel 6 and video:
Outdoor stabilization was absolutely acceptable !! and just a joy compared to garage testings; in the garage it took all my might and constant input to keep from destroying garage VS outdoors with 2-3mph winds was practically hands off ! very strange; zero trim and hands off; the FUN begins NOW>>>>>>>>>>>>>>>>
P.S. if you look up the link I provided in the above posting: note that my screen name there is "RootCanalGuy"
this looks like a dead thread, but I'll ask anyway.... is this description/process still relevant to the current reincarnation of the Ardupilot ? If so, there must be some changes over the last year and a half. What would have changed? I am in the throes of taming a tricopter and am looking for all the inside information I can find. Thanks for any and all responses.
Load 3.1rc7, do everything in Randy's AC3.0 pre-flight and maiden-flight videos, then run auto-tune and enjoy. You should have a very nicely flyable tri-copter.
Scott, I've gone to Randy's home page but the video link is greyed out. Not that familiar with where everything is for the AC yet, unfortunately. Can you either tell me where/how to find them, or give me a URL for them? Thanks again for your help.
I'm not sure where you're looking but they're all linked in the first post for the Arducopter 3.01 release thread: http://diydrones.com/forum/topics/arducopter-3-0-1-released
You can just search for Arducopter Randy on youtube to get a lot more good stuff.
Searching You Tube is how I finally found them. For some reason I couldn't find the release post. Thanks for the help. I've got it now. Now to see what I can do with all of this!
Hi Jazztech and everyone else. Dev team, thank you for all the work you guys have done and are doing.
My problem in non of the above, at least I don't think so. One particular Fortis Titan with an APM2.6, (the other is running a Pixhawk, Alhamdulillah no problems) is suffering from an oscillating servo. The moment it spools up the servo begins to osculate, right to left, back and forth, throughout the flight. Even during a successful AUTOTUNE!
We have tried changing props, parameters to no avail.
Any and all help to solve this is much appreciated. Log and parameter attached. azri_titan.param is the APM equipped oscillating servo Titan and titan.param is the Pixhawk Titan.